JPS60200200A - Radiation image converting panel - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] Unreleased 1J+ relates to a radiation image conversion panel used in a radiation image conversion method using a stimulable phosphor. More specifically, the present invention relates to a radiation image storage panel comprising a support, a phosphor layer made of a stimulable phosphor, an adhesive layer, and a protective film in this order.

[Technical Background of the Invention and Prior Art] As a method of obtaining radiographic images as images, the so-called radiographic method has conventionally used a combination of a radiographic film having an emulsion layer made of a silver salt photosensitive material and an intensifying screen. It's being used. Recently, a radiation image conversion method using a stimulable phosphor, as described in Japanese Patent Application Laid-Open No. 55-12145, has been attracting attention as an alternative method to the above-mentioned radiographic method. became. This radiation image conversion method uses a radiation image conversion panel (
It uses a stimulable phosphor sheet).

The radiation transmitted through the subject or the radiation emitted from the subject is absorbed by the stimulable phosphor of the panel, and then the stimulable phosphor is exposed to electromagnetic waves (excitation light) such as visible light and infrared rays in a time series. By exciting the stimulable phosphor, the radiation energy stored in the stimulable phosphor is released as fluorescence (stimulated luminescence), and this fluorescence is read photoelectrically to obtain an electrical signal. It is used to create images.

The above-mentioned radiation image conversion method has the advantage that a radiation image rich in information can be obtained with a much lower exposure dose than conventional radiography methods. Therefore, this radiation image conversion method has a very high utility value especially in direct medical radiography such as X-ray photography for the purpose of medical diagnosis.

The radiation image conversion panel used in the above radiation image conversion method has a basic structure consisting of a support and a phosphor layer provided on one side of the support. Note that a transparent protective film 14115I is generally provided on the surface of the phosphor layer opposite to the support (the surface not facing the support) to protect the phosphor layer from chemical alteration or Protects from physical impact. The protective film is normally provided on the phosphor layer by attaching a separately formed thin film using an adhesive.

The phosphor layer consists of a stimulable phosphor and a binder that contains and supports the stimulable phosphor in a dispersed state. After absorbing radiation such as X-rays, the stimulable phosphor absorbs visible light and When irradiated with electromagnetic waves (excitation light) such as infrared rays, it emits light (
It has the property of exhibiting (stimulated luminescence). Therefore, the radiation transmitted through the subject or emitted from the subject is absorbed by the phosphor layer of the radiation image conversion panel in proportion to the amount of radiation, and the radiation image of the subject or subject is displayed on the radiation image conversion panel. is formed as an accumulated image of radiation energy. This accumulated image can be emitted as stimulated luminescence by time-series excitation with the electromagnetic waves, and by photoelectrically reading this stimulated luminescence and converting it into an electrical signal, the accumulated image of radiation energy can be imaged. It becomes possible to convert into

'', the numerical ray image conversion method is a very advantageous image forming method as mentioned above, but the radiation image conversion panel used in this method is also different from the intensifying screen used in the conventional radiation q true method. Similarly, image quality (sharpness).

It is desirable that the image be able to produce images with good 11f (graininess, etc.).

In the radiation image conversion method, the sharpness of the image is determined not by the spread of stimulated luminescence light emitted from the phosphor of the radiation image conversion panel, but by the spread of excitation light within the panel. because.

The image of the radiation energy accumulated in the radiation image conversion panel is retrieved in chronological order, so if the customer is irradiated with excitation light that was irradiated to the panel within a certain period of time, the customer will be able to see if the excitation light was irradiated within that period of time. Although it is recorded as the output from a group of phosphor particles, if the excitation light spreads within the panel due to scattering etc. and excites phosphor particles existing outside the group of phosphor particles that are the irradiation target, the irradiation target This is because the output from a wider area than the phosphor particle group is recorded.

As a technology to improve the sharpness of radiation image conversion panels,
A method has been proposed in which the panel is colored with a colorant that absorbs excitation light. Regarding radiation image conversion panels colored with this coloring agent, for example,
No. 7-96300, specific examples of which include a support, a phosphor layer, and a support 1111! A typical radiation image conversion panel consisting of a panel in which at least one of the panels is colored is described.

When applying the 1-numerical ray image conversion method particularly to medical radiography, it is necessary to reduce the radiation dose to the human body and obtain more information, so the radiation image conversion panel used in the method has a low sensitivity. It is desirable to provide an image with as high a quality as possible and with as good an image quality as possible.For these reasons, it is desired to develop a technology that further improves the sensitivity and image quality of a radiation image conversion panel.

[Object of the Invention] An object of the present invention is to provide a radiation image conversion panel with improved image sharpness.

Another object of the present invention is to provide a radiation image conversion panel that is superior to -1 in both image sharpness and sensitivity.

The purpose of 1) above is to provide a radiation image conversion panel having a support, a phosphor layer comprising a supporting binder containing a stimulable phosphor in a dispersed state, an adhesive layer, and a protective film in this order. This can be achieved by the radiation image conversion panel of the present invention, wherein the agent layer is colored with a colorant that absorbs at least a part of the excitation light for causing the stimulable phosphor to stimulate luminescence. .

[Effects of the Invention] The present invention improves the sharpness of images obtained by coloring the adhesive layer provided between the phosphor layer and the protective film of the radiation image conversion panel. In addition, when comparing panels having the same sensitivity as described above, the present invention provides
The object of the present invention is to provide a radiation image conversion panel that provides images with better sharpness than known radiation image conversion panels.

As mentioned above, a protective film is generally adhered to the radiation image storage panel, and the installation of this protection IIS is generally done by attaching a separately formed transparent thin film onto the optical layer using an adhesive. This is done by contacting, i\i. According to the study of the wood inventor, a layer of thin adhesive (several #Lm
~ several tens of pLm) is colored with a colorant that selectively absorbs the excitation light for stimulating luminescence of the phosphor, and this colored adhesive layer efficiently absorbs the excitation light that spreads in the holding WItM. It has been found that the sharpness of the obtained image can be improved by

In addition, when a thin adhesive layer is colored as described above, sharpness can be improved without significantly reducing sensitivity compared to when a thicker layer such as a phosphor layer is colored. It turns out that it can be improved. That is, by coloring a thin adhesive layer, absorption of stimulated luminescence light in the colored layer can be minimized.

In addition, it is capable of efficiently absorbing excitation light that has spread within the protective film due to scattering or the like.

Therefore, when the radiation image conversion panel of the present invention is made to have the same sensitivity as the known radiation image conversion panel in which the phosphor layer is colored, the layer thickness of the light layer can be made thinner. , thereby further improving the sharpness in the single-sensitivity comparison. In other words, this means that in comparison of the same sharpness, the sensitivity can be made more within the layer.

[Structure of the Invention] The radiation image conversion panel of the present invention having the preferable characteristics as described above can be manufactured, for example, by the method described below.

The support used in unreleased IJJ can be arbitrarily selected from various materials used as supports for intensifying screens in conventional radiography or materials known as supports for radiation image conversion springs. be able to. Examples of such materials include films of cellulose acetate, polyester, polyethylene terephthalate, polyamide, polyimide, triacetate materials, metal sheets such as aluminum foil, aluminum alloy foil, ordinary paper, baryta paper, and resin coating. Examples include paper, pigment paper containing pigments such as titanium dioxide, and paper sized with polyvinyl alcohol. However, in consideration of the characteristics and handling of the radiation image storage panel as an information recording material, a particularly preferred material for the support in the present invention is a plastic film. This plastic film may be kneaded with a light-absorbing substance such as carbon black, or may be kneaded with a light-reflecting substance such as titanium dioxide.

The former is a support suitable for a high sharpness type radiation image conversion panel, and the latter is a support suitable for a high sensitivity type radiation image conversion panel.

In known radiation image conversion panels, a phosphor layer is provided in order to strengthen the bond between the support and the phosphor layer, or to improve the sensitivity or image quality (sharpness, granularity) of the radiation image conversion panel. A polymeric substance such as gelatin is coated on the surface of the support on the side to be coated to form an adhesion imparting layer, or a light reflective layer made of a light reflective substance such as titanium dioxide, or a light absorbing substance such as carbon black. Providing a light absorption layer is also practiced. The support used in the unexposed layer 1 can also be provided with these various layers, and the configuration thereof can be arbitrarily selected depending on the purpose, use, etc. of the desired radiation image storage panel.

Furthermore, 1. +1 As described in Japanese Patent Publication No. 58-200200, in order to improve the sharpness of the obtained image, the surface of the support on the phosphor layer side (the surface of the support on the phosphor layer side) (If an adhesion-imparting layer, light-reflecting layer, light-absorbing layer, etc. is provided, this means the surface thereof)
The fine unevenness may be uniformly formed.

Next, a phosphor layer is formed on the support.

The phosphor layer is basically a layer consisting of a binder that inherently supports particles of the stimulable phosphor in a dispersed state.

As mentioned above, a stimulable phosphor is a phosphor that exhibits stimulated luminescence when irradiated with radiation and then irradiated with excitation light.
From a practical standpoint, a phosphor that exhibits stimulated luminescence in a wavelength range of 300 to 500 nm by excitation light in a wavelength range of 400 to 900 nm is desirable. Examples of stimulable phosphors used in the radiation image conversion panel of the present invention include:

SrS:Ce, Sm, SrS:Eu as described in US Pat. No. 3,859,527.

Sm, Th02:E r, and La2O2S:E
u, Sm, ZnS described in JP-A-55-12142
:Cu, Pb, BaO*xAl2O3:Eu (however,
0.8≦X≦10), and M”0−xsi02:A
(However, Mn is Mg, Ca, Sr, Zn, Cd, or Ba, and A is Ce, Tb, Eu, Tm, Pb, T
1. B i or Mn, and X is 0.5≦X≦2
．． 5), CB described in JP-A-55-12143
al-X=y l Mgx l c ay) FX
:aEu2+ (However, X is at least one of C1 and Br, X and y are 0, X+y≦0,
6. and xyso-r, a is 1O-1l≦a≦5
X l m”).

LnO described in JP-A-55-12144
X: xA (Ln is La, Y, Gd, and Lu
X is at least one of 0 sentences and Br, A is at least one of Ce and Tb, and X is O<x<0.1), JP-A It is described in Publication No. 55-12145 (B
a l−X, M2+X) FX: y A (However, M2+ is Mg, Ca, Sr, Zn, and Cd(
7) At least one of them, X is Cl, Br, and I
At least one of A is Eu, Tb, Ce, Tm
, Dy, Pr, Ho, Nd, Yb, and Er, and X is 0≦X≦o, 6. y is
O≦y≦0.2), JP-A-55-160078
M” FX* xA: yL described in the publication No.
n [However, 9M” is Ba, Ca, Sr, Mg, Zn,
and at least one of Cd(7), A is Bed,
MgO, Ca0.5rO1BaO1ZnO, AjL20
3. Y2O3, La2O3, In2O3, 5i02.
TlO□, ZrO2,GeO2,5n02,
At least one of N b 205, T a 205, and Th02, Ln is Eu, Tb, Ce, Tm,
Dy, Pr, Ho, Nd, Yb, Er, Sm,
and at least one of Gd, X is 0 sentences, Br,
and ■, where X and y are respectively 5X10-≦X≦0.5 and o<y≦0.
A phosphor represented by the composition formula: 2.

It is described in Japanese Patent Application Laid-open No. 116777/1983 (B
at-X, M”x)F2 e aBaX2 :yEu
, zA [However, M is at least one of beryllium, magnesium, calcium, strontium, zinc, and cadmium, or at least one of chlorine, bromine, and iodine, and A is at least one of zirconium and scandium. Yes, a, x, y, and 2 are each 0.5≦a≦1.25.0≦X≦1.
104≦y≦2 X I O-', and O<z≦10
A phosphor represented by the composition formula "-", JP-A-57
-23673 (BFL l
-x, M''X) F2・aBaX
2: yEu, zB [However, M irises are beryllium, magnesium, calcium, strontium, and zinc.

and at least one of cadmium, X is chlorine,
At least species of bromine and iodine, a
, x, y, and 2 are each 0.5≦a≦1.25.
0≦X≦1. lO'≦y≦2×10−', and O<z
≦jX10-'.

It is described in Japanese Patent Application Laid-Open No. 57-23675 (B
at-x, M”X) F2 * aBaX2 :yE
u, zA [However, Mll is at least one of beryllium, magnesium, calcium, strontium, zinc, and cadmium, X is at least one of chlorine, bromine, and iodine, and A is at least one of arsenic and silicon. At least one type, a, x, y, and 2 are respectively 0.5≦a≦1.25, 0≦X≦1, 10
-≦y≦2×10-' and O<z≦5XIO-'] A phosphor represented by the composition formula: -≦y≦2×10-' and O<z≦5XIO-';
X: xCe [However, 1M! are Pr, Nd, Pm, Sm,
Eu, Tb, Dy, Ho, Er, Tm, Yb, and B
at least one trivalent metal selected from the group consisting of i, X is one or both of C1 and Br, and X is O<x<0.1. A phosphor B described in Japanese Patent Application Laid-Open No. 58-206678
a 1- )c M z /2 L X72 F X
: y E u ” [However, M is Li, Na,
Represents at least one alkali metal selected from the group consisting of Rh and Cs; L is Sc, Y, La, and Cs;
e, Pr, Nd, 'Pm, Sm, Gd, Tb, Dy, H
o, Er, Tm, Yb, Lu, AfL, Ga
, In, and Tl; X represents at least one type of /\logen selected from the group consisting of C1, Br, and ■; and X represents lO '≦X≦0.5, y is O
y≦0.1].

BaFX@xA described in Japanese Patent Application No. 57-137374 filed by the present applicant: yEu2+ [However,
X is at least one halogen selected from the group consisting of C1, Br, and I; A is a fired product of a tetrafluoroboric acid compound; and X is 10"≦X
≦ o, i, y are O x y ≦ 0.1] The BaFX dispute xA:yEu” [ However, X is at least one halogen selected from the group consisting of CM, Br, and I; A is a monovalent or divalent metal salt of hexafluorosilicic acid, hexafluorotitanic acid, and hexafluorozirconic acid; is a fired product of at least one compound selected from the hexafluoro compound group consisting of; and X is 10'≦X≦0°1.7
is a phosphor represented by the composition formula: o<y≦0.1.

BaFX x NaX': aEu2+ [where X and X'' are C1, T3r, and I
A phosphor that is at least one of

M"FX*xNaX':yEu total:
Z A [However, Ml is Ba, Sr, and Ca
X and X'' are at least one halogen selected from the group consisting of C1, Br, and !; A is at least one halogen selected from the group consisting of;

is at least one transition metal selected from V, Cr, Mn, Fe, Co, and Ni; and X is 0<x
≦2. V is 0<7≦0.2. and 2 is 0<z≦104
A phosphor represented by the composition formula M ” F X * a M ”
・bM"X", e cM"X"'3 a xA:
y E u- [where yIN is Ba, Sr, and C
at least one alkaline earth metal selected from the group consisting of a; Ml is Li, Na, Rh, and C;
M is at least one divalent metal selected from the group consisting of Be and Mg; MN is IQ, G
at least one divalent metal selected from the group consisting of a, In, and TJJ; A is a metal oxide;
is at least one kind of halogen selected from the group consisting of C1, Br, and I;
is at least one halogen selected from the group consisting of F, (, Q, Br, and I; and.

a is O≦a≦2, b is 0≦b≦to-', C is 0≦C≦
lO'4, and a+b+c≧104; X is O<x
≦0.5, y is 0 and y≦0.2].

etc. can be mentioned.

Among the two stimulable phosphors, divalent europium-activated alkaline earth metal fluorohalide phosphors and rare earth element-activated rare earth oxyhalide phosphors exhibit high-brightness single emission. Therefore, the stimulable phosphor used in the present invention is not limited to the above-mentioned phosphors, but is particularly preferable.The stimulable phosphor used in the present invention is not limited to the above-mentioned phosphors, but is a phosphor that exhibits stimulated luminescence when irradiated with radiation and then irradiated with excitation light. It can be anything.

Examples of binders for the phosphor layer include proteins such as gelatin,
Polysaccharides such as dextran, or natural polymeric substances such as gum arabic; and polyvinyl butyral, polyvinyl acetate, nitrocellulose, ethylcellulose, vinylidene chloride-vinyl chloride copolymer, polyalkyl (meth)acrylate, vinyl chloride/vinyl acetate Binders typified by synthetic polymeric materials such as copolymers, polyurethanes, cellulose acetate butyrate, polyvinyl alcohol, linear polyesters, etc. may be mentioned. Particularly preferred among such binders are nitrocellulose, linear polyester,
These are polyalkyl (meth)acrylates, mixtures of nitrocellulose and linear polyesters, and mixtures of nitrocellulose and polyalkyl (meth)acrylates.

Note that these binders may be crosslinked with a crosslinking agent.

The phosphor layer can be formed on the support, for example, by the following method.

First, the stimulable phosphor described in t. and a binder are added to a suitable solvent and thoroughly mixed to prepare a coating solution in which phosphor particles are uniformly dispersed in the binder solution.

Examples of solvents for coating liquid vA include lower alcohols such as methanol, ethanol, n-propanol, and n-butanol; chlorine-containing hydrocarbons such as methylene chloride and ethylene chloride; acetone, methyl ethyl ketone, and methyl isobutyl ketone. Ketones: esters of lower fatty acids and lower alcohols such as methyl acetate, ethyl acetate, and butyl acetate; ethers such as dioxane, ethylene glycol monoethyl ether, and ethylene glycol monomethyl ether; and mixtures thereof. .

The mixing ratio of the binder and the stimulable phosphor in the coating solution varies depending on the characteristics of the intended radiation image conversion panel, the type of phosphor, etc., but generally the mixing ratio of the binder and the stimulable phosphor is 1. :1 to 1:100 (weight ratio), and particularly preferably from 1.8 to 1:40 (weight ratio).

The coating solution contains a dispersant to improve the dispersibility of the phosphor in the coating solution, and a dispersant to improve the bonding force between the binder and the phosphor in the phosphor layer after formation. Various additives, such as plasticizers, may be mixed to make the material more durable. Examples of dispersants used for such purposes include:
Examples include phthalic acid, stearic acid, caproic acid, and lipophilic surfactants. Examples of plasticizers include phosphate esters such as triphenyl phosphate, tricresyl phosphate, and diphenyl phosphate; phthalate esters such as diethyl phthalate and dimethoxyethyl phthalate; ethyl phthalyl ethyl glycolate, butyl phthalate, etc. and polyesters of polyethylene glycol and aliphatic dibasic acids, such as polyesters of triethylene glycol and adipic acid, and polyesters of diethylene glycol and amber.

The coating solution containing the phosphor and binder prepared as described above is then uniformly applied to the surface of the support to form a coating film of the coating solution. This coating operation can be carried out using conventional coating means such as a doctor blade, roll coater, knife coater, etc.

Then, the formed coating film is gradually heated and dried to complete the formation of the phosphor layer on the support 42. The thickness of the phosphor layer varies depending on the characteristics of the intended radiation image conversion panel, the type of phosphor, the mixing ratio of the binder and the phosphor, and is usually 20 gm to 1 mm. However, the thickness of this layer is preferably 50 to 500 μm.

Note that the phosphor layer does not necessarily have to be a support as described above.
It is not necessary to directly apply a coating liquid to the surface of the phosphor layer. After that, the support and the phosphor layer may be bonded by pressing it onto the support or using an adhesive.

Next, a protective film is provided on the phosphor layer via a colored adhesive layer, which is a characteristic feature of the present invention.

Examples of adhesives used in the adhesive layer in the radiation image storage panel of the present invention include polyacrylic resins, polyester resins, polyurethane resins, polyvinyl acetate resins, and ethylene/vinyl acetate copolymers. be able to. The adhesive is not limited to the above-mentioned resins, and for example, any resin conventionally known as an adhesive can be used.

Furthermore, the coloring agent used to color the adhesive layer is a coloring agent that absorbs at least a portion of the excitation light for causing the stimulable phosphor constituting the phosphor layer of the panel to stimulate luminescence. It is a drug. This colorant has reflective properties such that the average reflectance in the excitation light wavelength region of the stimulable phosphor used in the panel is smaller than the average reflectance in the stimulated emission wavelength region of the stimulable phosphor. tIT is desirable.

From the point of view of "direction of image sharpness," the average reflection (l) in the excitation light wavelength region of the photostimulable phosphor of the colorant is preferably as small as possible.On the other hand, from the viewpoint of sensitivity, It is preferable that the average reflectance of the phosphor in the stimulated emission wavelength region be as large as possible.

Therefore, preferred colorants vary depending on the type of stimulable phosphor used in the radiation image storage panel.

As mentioned above, the phosphor used in the radiation image conversion panel of the present invention may be a phosphor that exhibits stimulated luminescence in the wavelength range of 300 to 500 nm by excitation light in the wavelength range of 400 to 900 nm. desirable. For such stimulable phosphors, blue to A green colorant is used.

Examples of blue to green colorants (dyes and pigments) preferably used in the present invention include JP-A No.
Colorants such as those disclosed in Japanese Patent Application No. 163500, such as Zapon Fast Blue 30 (manufactured by Kist), Nistrol Prill Blue h13RL (manufactured by Sumitomo Chemical), Sumia Acrylic Blue F-GSL (manufactured by Sumitomo Chemical) D & C Blue No. 1 (manufactured by National Aniline), Subirin Blue (manufactured by Hodogaya Chemical), Oil Blue No. 603 (manufactured by Orient), Kitten Blue A (manufactured by Chipakaigy), Crampons force Chironpur-G
LH (manufactured by Hodogaya Chemical Hina), Lake Blue A, F, H (
Kyowa Jr. Co., Ltd.), Rhodalin Blue 6GX (Kyowa Sangyo Co., Ltd.), Brimodianin 6GX (Inabata Sangyo Co., Ltd.), Prill Acid Green 6BH (Hodogaya Chemical Co., Ltd.), Cyanine Blue BNR3 (Toyo Ink Co., Ltd.), Lio Examples include organic colorants such as Norblue SL (manufactured by Toyo Ink Co., Ltd.); and inorganic colorants such as ultramarine blue, cold blue, cerulean blue, chromium chloride, and Ti02-ZnO-Coo-N1O pigments. 6 Also, color index No. as disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 57-96300.

24411.23160.74180.74200.2
2800.23150.23155.24401.14
880.15050.15706.15707.179
41.74220.13425.13361,1342
0.11836.74140.74380.74350
, and organic metal complex salt colorants such as 74460.

Among these blue to green coloring agents, from the viewpoint of graininess and contrast of the obtained image, the latter, as disclosed in Japanese Patent Laid-Open No. 57-96300, has a wavelength longer than that of the excitation light. Particularly preferred are organic metal complex colorants that do not emit light.

The colored adhesive layer can be formed on the phosphor layer together with the protective layer, for example, by the following method.

First, the above resin and colorant are added to a suitable solvent and mixed thoroughly to prepare a coating solution for forming an adhesive layer. As the solvent for preparing the coating solution, the solvent used in forming the phosphor layer described above can be used.

This coating liquid is uniformly applied to the surface of a transparent thin film for a protective film to form a coating film by using a conventional coating means such as a tractor, roll coater, knife coater, etc. Next, the transparent thin film with the coating film formed thereon is adhered (laminated) to the phosphor layer 2 with the coating facing down, thereby forming a colored adhesive layer and a protective film on the phosphor layer 1-. Complete.

In this way, a colored adhesive layer is formed on the phosphor layer. The thickness of the colored adhesive layer varies depending on the characteristics of the radiation image storage panel to be used, the types of materials used for the phosphor layer and protection +19, the types of resins and colorants, etc., but it is usually from O6 to It is preferable to set it to 10 pLm.

In addition, the mixing ratio of resin and colorant in the coating liquid is generally 10:1 to 106:1 when the colorant is a dye.
1 (weight ratio).

When the colorant is a pigment, generally 1:10 to 105
:1 (weight ratio).

From the viewpoint of sensitivity, it is preferable that the reflectance of the colored adhesive layer in the stimulated emission wavelength region be as large as possible.

Generally, it is preferable that the average reflectance of the colored adhesive layer in the rr% luminescence wavelength range is 20% or more of the f average reflectance of an equivalent non-colored adhesive layer in the same wavelength range.

In terms of sharpness, the smaller the reflectance of the colored adhesive layer in the excitation light wavelength region, the better. Generally, the average reflectance of the colored adhesive layer in the excitation light wavelength region is preferably 95% or less of the average reflectance of an equivalent uncolored adhesive layer in the wavelength region.

However, in the present invention, reflectance means reflectance measured using an integrating spherical spectrophotometer.

Furthermore, examples of the material for the transparent protective film formed as described in 1- above include transparent thin films separately formed from polyethylene terephthalate, polyethylene, vinylidene chloride, polyamide, and the like. The thickness of the transparent protective film is preferably about 3 to 20 pLm.

Next, Examples and Comparative Examples of the present invention will be described.

However, each of these aspects does not limit the invention.

[Example 11 Monovalent europium activated fluorobromide/helium phosphor (B
Methyl ethyl ketone was added to a mixture of aFBr:Eu2+) particles and an acrylic resin to prepare a dispersion containing phosphor particles in a dispersed state.

After further adding tricresyl phosphate, n-butanol, and methyl ethyl ketone to this dispersion, they were thoroughly stirred and mixed using a propeller mixer to uniformly disperse the phosphor particles and adjust the mixing ratio of the binder and the phosphor. A coating liquid having a weight ratio of 1+30 and a viscosity of 25 to 35 PS (at 25°C) was prepared.

Next, polyethylene terephthalate sheet T-(support,
A sheet (thickness: 250 gm) was placed horizontally on a glass plate 1-, and the coating liquid was applied uniformly thereto using a doctor blade. After coating, the support on which the coating film has been formed is placed in a dryer, and the temperature inside the dryer is adjusted from 25°C to 100°C.
The temperature was gradually raised to 0.degree. C., and coating + 1Q drying was performed. In this way, a phosphor layer having a layer thickness of about 300 gm was formed on the support. □ Separately, polyester MA resin (adhesive; Vylon #300
, manufactured by Toyobo ■) in methyl ethyl ketone,
A coating solution was prepared by adding dye (copper phthalocyanine) to this adhesive solution in an amount of 0.5% in terms of solid content relative to the adhesive.

This coating solution was applied to a polyethylene terephthalate transparent film (protective film, thickness: 12IL) by the same operation as above.
m) 2 g/rrf was applied to J- to form a coating film consisting of a colored adhesive.

Then, by placing the transparent film provided with the coating made of this colored adhesive with the coating side facing down and adhering it to the phosphor layer, a colored adhesive layer and a transparent protective film are formed, and the support is , a radiation image storage panel was produced which was composed of a phosphor layer, a colored adhesive layer and a transparent protective film. (Panel a) Furthermore, the star of the dye used for coloring the adhesive layer is o, t.
-t, o% (solid content relative to the adhesive: 1) to produce various colors with different degrees of coloring of the adhesive layer composed of the support, the phosphor layer, the colored adhesive layer, and the transparent protective film. A radiation image conversion panel was manufactured. (Panel A) [Comparative Example 1] Example 1 except that 0.1% (solid content ratio to binder) of dye (copper phthalocyanine) was added to the coating solution for forming the phosphor layer. A colored phosphor layer was formed on the support 2 by carrying out the same treatment as in method 1.

Next, by performing the same treatment as in Example 1 except that no dye was added to the coating solution for forming the adhesive layer, the support, the colored phosphor layer, the adhesive layer, and the transparent layer 1! ! A radiation image storage panel constructed from one protective film was manufactured. (
Panel b) Furthermore, A1? The amount of dye used to color the light layer is 0.1
By changing the solid content ratio to -1.0% (solid content ratio to binder), the phosphor layer composed of the support, the colored phosphor layer, the adhesive layer and the transparent protective film can be produced with different degrees of coloring. A radiation image conversion panel was manufactured. (Panel B) Each radiation image conversion panel obtained as described above (
Panel a, A and panel b, B) were evaluated by the image sharpness test and sensitivity test described below.

(1) Image sharpness test MT X-rays with a tube voltage of 80 KVp are applied to the radiation image conversion panel.
After irradiating through the F chart, the phosphor particles are excited by scanning with He-Ne laser light (wavelength: 632.8 nm), and the stimulated luminescence emitted from the phosphor layer is transferred to a receiver (spectral sensitivity S-5). The light was received by a photomultiplier (photomultiplier tube) and converted into an electrical signal, which was reproduced as an image by an image reproducing device to obtain an image of MTF Char I on a display device. The modulation transfer function (MTF) was measured from the obtained image.

(2) Sensitivity test After irradiating the radiation image conversion panel with X-rays with a tube voltage of 80 KVp,
m) and the sensitivity was measured.

The results obtained regarding image sharpness are shown in graphical form in FIG.

Figure 1 shows the following: Curve a: The relationship between spatial frequency and MTF value in panel a (Example 1), and Curve b: The relationship between spatial frequency and MTF value in panel b (Comparative example 1). each represents.

The results obtained regarding image sharpness and sensitivity are also shown in graph form in FIG.

In Fig. 2, the horizontal axis is the difference in relative sensitivity between panel b in Comparative Example 1 (relative sensitivity: 100, sharpness at spatial frequency 2 cycles/mm = 35%) and 1 (
Similarly, the vertical axis represents the difference in sharpness (increase) when panel b is used as a reference. In FIG. 2, straight line A: relationship between relative sensitivity and sharpness in panel A (Example 1), and straight line B: relationship between relative sensitivity and sharpness in panel B (comparative example 1).

each represents.

As is clear from the results summarized in FIG. 1, the radiation image conversion panel of the present invention (panel a) has significantly improved sharpness compared to the conventional radiation image conversion panel (panel b).

Furthermore, from graphs A and B shown in FIG.
It is clear that this method provides images with significantly higher sharpness than those disclosed in Japanese Patent Application Laid-Open No. 57-96300.

[Example 2] In Example 1, the layer thickness of the phosphor layer was 150I1. A radiation image storage panel composed of a support, a phosphor layer, a colored adhesive layer, and a transparent protective film was manufactured by carrying out the same treatment as in Example 1 except that m was used.

Furthermore, the amount of dye used for coloring the adhesive layer is 0.1 to 1.
．． By changing the solid content ratio to 0% (solid content ratio to adhesive), various radiation image conversions with different degrees of coloring of the adhesive layer composed of a support, a phosphor layer, a colored adhesive layer, and a transparent protective film can be achieved. Manufactured the panel. () Gunnel C) [Comparative Example 2] In Comparative Example 1, the layer thickness of the colored phosphor layer was 150 pLm.
A radiation image conversion panel comprising a support, a colored phosphor layer, an adhesive layer and a transparent protective film was manufactured by carrying out the same treatment as in Comparative Example 1 except for the following. (Panel d) Next, each of the obtained radiation image conversion panels (Panels C and d) was evaluated by the above image sharpness test and sensitivity test.

The results obtained are shown in graphical form in FIG.

In FIG. 2, straight line C: represents the relationship between relative sensitivity and sharpness in panel C (Example 2). In this case, panel d is used as a reference.
(Relative sensitivity = lOO1 spatial frequency 2 cycles/mm
(sharpness = 55%) is used.

From graph C shown in FIG. 2, it is clear that the radiation image storage panel according to the present invention exhibits a similar tendency even when the thickness of the phosphor layer is made thinner, and is sharper than the conventional radiation image storage panel at the same sensitivity. It is clear that the degree of improvement is improved.

[Brief explanation of drawings]

FIG. 1 shows the MT of the radiation image conversion panel of the present invention (curve a) and the conventional radiation image conversion panel (curve b).
It is a graph showing F. ; Figure 52 shows the radiation image conversion panel of the present invention (straight lines A and C
) and a known radiation image conversion panel (straight line B) is a graph showing the relationship between relative sensitivity and sharpness. Patent applicant Fuji Photo Film Co., Ltd. % Agent Patent attorney Yasuo Yanagawa Figure 1 0 0.5 1 +, 5 2 2.5 3 Spatial circumference] Skin number (cycles/mm)

Claims (1)

[Claims] ■. In a radiation image conversion panel having a support, a phosphor layer comprising a supporting binder containing a stimulable phosphor in a dispersed state, an adhesive layer, and a protective film in this order, the adhesive layer is stimulable. 1. A radiation image conversion panel characterized in that the panel is colored with a coloring agent that absorbs at least a portion of excitation light for stimulating a phosphor to emit light. 2゜The adhesive layer is colored with a colorant whose average reflectance in the excitation light wavelength region of the stimulable phosphor is smaller than the average reflectance in the stimulated emission wavelength region of the stimulable phosphor. A radiation image conversion panel according to claim 1, characterized in that: 3゜J-Excitation light wavelength range of colored adhesive layer 95%
It is extremely disrespectful to be below 4! #￥F, radiographic image conversion panel described in item 2 of Jōme Musiki. 4゜The colored adhesive layer has an average reflectance in the stimulated emission wavelength range of 20% or more of the average reflectance in the stimulated emission wavelength range of an equivalent non-colored adhesive layer. A radiation image conversion panel according to claim g<2. 5.41 The stimulable phosphor is a phosphor that exhibits stimulated luminescence in the wavelength range of 300 to 500 nm by excitation light in the wavelength range of 400 to 900 nm. The radiation image conversion panel according to any one of Items 1 to 4. 6. The radiation image storage panel according to claim 5, wherein the stimulable phosphor is a divalent europium activated alkaline earth metal fluorohalide phosphor. 7. The radiation image conversion panel according to claim 5, wherein the stimulable phosphor is a rare earth element-activated rare earth oxyhalide phosphor.